1. Field of the Invention
The present invention relates to a camera apparatus to which a lens unit is attachable/detachable. The present invention also relates to a camera system having a camera unit and a lens unit exchangeable with respect to the camera unit. In particular, the present invention relates to a system in which a camera unit and a lens unit can communicate with each other so that unique information of the lens unit can be communicated to the camera unit.
2. Description of Related Art
Recently, in a camera system of an exchangeable lens system, respective driving systems such as focus driving means, exposure driving means, and zoom driving means are provided on a lens unit side, and control means for controlling the respective driving systems on the lens unit side is provided on a camera unit side. Furthermore, the camera system includes communication means enabling control data to be communicated between the camera unit and the lens unit. The camera unit and the lens unit are configured so as to communicate lens data information, various pieces of control information, or status information unique to a lens via the communication means, whereby the operation on the lens unit side can be controlled from the camera unit side.
The above-described configuration in which a camera unit can be communicated with a lens unit is described, for example, in JP 4(1992)-280239 A. In a camera system with an exchangeable lens system described in JP 4(1992)-280239 A, in order for various kinds of lens units to be used, when a lens unit is mounted on a camera unit, setting information (lens data) set uniquely with respect to a lens is transmitted to the camera unit. On the camera unit side, various kinds of settings suitable for the lens unit mounted on the camera unit are performed based on the lens data transmitted from the lens unit.
Furthermore, JP 2005-173314 A discloses a configuration in which a camera system is set based on the mounting history of an accessory. Specifically, when an accessory such as an exchangeable lens is mounted on a camera unit, the camera unit obtains identification information from the accessory. The camera unit determines whether or not the accessory has been mounted previously, based on the identification information obtained from the accessory. In the case of determining that the accessory has been mounted previously, the camera unit applies the settings of the camera system with respect to the accessory that was mounted previously to the current settings.
However, according to the above-mentioned conventional configuration, when the lens unit is mounted on the camera unit, or when the camera unit with the lens unit mounted thereon is switched on, the camera unit performs processing of acquiring lens data from the lens unit, so that it takes a long time to obtain a photographable state from the time at which the lens unit is mounted on the camera unit or the time at which the camera unit is switched on. This lets a shutter chance slip away, causing a decrease in ease of operation.
More specifically, the conventional camera unit performs processing of acquiring lens data that is information unique to a lens from the lens unit every time the camera unit is switched on. The camera unit performs a setting such as autofocusing control, autoexposure control, or zoom control, based on the lens data acquired from the lens unit. The transmission/reception of lens data and the settings in the camera unit as described above are performed every time the camera unit is switched on, so that there is a problem that the state cannot be shifted to a photographable state immediately after the camera system is switched on.
Furthermore, a high-performance exchangeable lens has a large amount of lens data. When the amount of lens data is large, it takes a long time for the transmission/reception of lens data between the camera unit and the lens unit, which slows down the start-up of the camera system. Particularly, according to the configuration in which lens data is transmitted to the camera unit every time the camera system is switched on as in the prior art, and various kinds of settings are performed in the camera unit, the start-up of the camera system becomes much slower.